EP2973726A1 - Magnetic random access memory cells with isolating liners - Google Patents
Magnetic random access memory cells with isolating linersInfo
- Publication number
- EP2973726A1 EP2973726A1 EP14779176.8A EP14779176A EP2973726A1 EP 2973726 A1 EP2973726 A1 EP 2973726A1 EP 14779176 A EP14779176 A EP 14779176A EP 2973726 A1 EP2973726 A1 EP 2973726A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- magnetic
- liner
- etch
- layer
- manufacturing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/01—Manufacture or treatment
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/10—Magnetoresistive devices
Definitions
- the invention relates generally to memory devices. More particularly, the invention relates to memory devices including magnetic random access memory (“MRAM”) cells with isolating liners to prevent shunting.
- MRAM magnetic random access memory
- MRAM devices have become the subject of increasing interest, in view of the discovery of magnetic tunnel junctions having a strong magnetoresistance at ambient temperatures.
- MRAM devices offer a number of benefits, such as faster speed of writing and reading, non-volatility, and insensitivity to ionizing radiations. Consequently, MRAM devices are increasingly replacing memory devices that are based on a charge state of a capacitor, such as dynamic random access memory devices and flash memory devices.
- a MRAM device in a conventional im lementation, includes an array of MRAM cells, each one of which includes a magnetic tunnel junction formed of a pair of ferromagnetic layers separated by a thin insulating layer.
- One ferromagnetic layer, the so-called reference layer is characterized by a magnetization with, a fixed direction
- the other ferromagnetic layer, the so-called storage layer is characterized by a magnetization with a direction that is varied upon writing of the device, such as by applying a magnetic field.
- a resistance of the magnetic tunnel junction is high, namely having a resistance value Rmax corresponding to a high logic state "1".
- the resistance of the magnetic tunnel junction is low, namely having a resistance value Rmin corresponding to a low logic state "0".
- a logic state of a MRAM cell is read by comparing its resistance value to a reference resistance value Rref, which is derived from a reference cell or a group of reference ceils and represents an in-between resistance value between that of the high logic state "1 " and the low logic state "0".
- a MRAM device is conventionally manufactured by photolithography, in which a photoresist is used as a soft mask for patterning a stack of magnetic layers. Specifical ly, a photoresist layer is formed on the stack of magnetic layers, and the photoresist layer is then patterned to form an array of dots. Portions of the stack of magnetic layers exposed by the array of dots are then etched away to form a corresponding array of MRAM cells.
- the photoresist layer is stripped to result in a MRAM device.
- the above-described manufacturing method can suffer from certain deficiencies.
- One such deficiency is that during a magnetic stack etch sputtered material may accumulate on the previously etched magnetic stack. The sputtered material may subsequently cause shunting of magnetic layers across a tunnel barrier layer.
- a manufacturing method to form a memory device includes forming a hard mask on a magnetic stack.
- a first magnetic stack etch is performed to form exposed magnetic layers.
- a liner is applied to the exposed magnetic layers to form protected magnetic layers.
- a second magnetic stack etch forms a magnetic random access memory (M RAM) cell, where the liner prevents shunting between the protected magnetic layers.
- M RAM magnetic random access memory
- a memory device includes an M RAM cell comprising a magnetic stack with exposed magnetic layers and a liner preventing shunting between protected magnetic layers.
- FIG. 1 illustrates processing operations associated with an embodiment of the invention.
- FIG . 2 illustrates an MRAM cell with a hard mask on a set of magnetic layers.
- FIG. 3 illustrates the results of a first magnetic stack etch performed in accordance with an embodiment of the invention.
- FIG. 4 illustrates isolating liner deposition performed in accordance with an embodiment of the invention.
- FIGURE 5 illustrates the results of a second magnetic stack etch performed in accordance w it an embodiment of the invention.
- a set refers to a collection of one or more objects.
- a set of objects can include a single object or multiple objects.
- Objects of a set also can be referred to as members of the set.
- Objects of a set can be the same or different.
- objects of a set can share one or more common characteristics.
- the terms “substantially” and “substantial” refer to a considerable degree or extent. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation, such as accounting for typical manufacturing tolerances or variability of the embodiments described herein.
- adjacent refers to being near or adjoining. Adjacent objects can be spaced apart from one another or can be in actual or direct contact with one another. In some instances, adjacent objects can be formed integrally with one another.
- connection refers to an operational coupling or linking.
- Connected objects can be directly coupled to one another or can be indirectly coupled to one another, such as via another set of objects.
- main group element refers to a chemical element in any of
- a main group element is also sometimes referred to as a s- block element or a p-block element.
- transition metal refers to a chemical element in any of
- a transition metal is also sometimes referred to as a d-block element.
- Figure 1 illustrates processing operations associated with an embodiment of the invention.
- a hard mask is deposited and patterned on a set of magnetic layers 10.
- Figure 2 illustrates an MRAM cell 100 with a hard mask 102 deposited and etched on a set of magnetic layers 103.
- the hard mask material may be metallic or dielectric. Photoresist used to form the hard mask 102 has been removed and therefore Figure 2 only illustrates the remaining hard mask 102.
- the MRAM cell 100 is implemented as a magnetic tunnel junction, and includes a storage layer 106, a reference layer 110, and an insulating layer 108 that is disposed between the storage layer 106 and the reference layer 1 10.
- Each of the storage layer 106 and the reference layer 110 includes, or is formed of, a magnetic material and, in particular, a magnetic material of the ferromagnetic type.
- the storage layer 106 and the reference layer 110 can include the same ferromagnetic material or different ferromagnetic materials. Examples of suitable ferromagnetic materials include transition metals, rare eart h elements, and their alloys, either with or without main group elements.
- suitable ferromagnetic materials include iron (“Fe”), cobalt (“Co”), nickel (“Ni”), and their alloys, such as permalloy (or Ni80Fe20); alloys based on Ni, Fe, and boron (“B”); Co90FelO; and alloys based on Co, Fe, and B.
- a thickness of each of the storage layer 106 and the reference layer 1 10 can be in the nanometer (“ran”) range, such as from about 1 nm to about 20 nm or from about 1 nm to about 10 nm.
- the insulating layer 108 functions as a tunnel barrier, and includes, or is formed of, an insulating material.
- suitable insulating materials include oxides, such as aluminum oxide (e.g., A1203) and magnesium oxide (e.g., MgO).
- a thickness of the insulating layer 108 can be in the nm range, such as from about 1 nm to about 10 nm.
- the MRAM cell 100 also includes a pinning layer 112, which is adjacent to the reference layer 1 10 and, through exchange bias, stabilizes a magnetization of the reference layer 110 along a particular direction when a temperature within, or in the vicinity of, the pinning layer 112 is lower than a blocking temperature TBR, or another threshold
- the MRAM ceil 100 is implemented for thermally assisted switching ("TAS"), and the storage layer 106 is also exchange biased by another pinning layer 104, which is adjacent to the storage layer 106 and is characterized by a blocking temperature TBS, or another threshold temperature, which is smaller than the blocking temperature TBR. Below the blocking temperature TBS, a magnetization of the storage layer 106 is stabilized by the exchange bias, thereby retaining a stored logic state in accordance with a direction of that magnetization. Writing is carried out by heating the MRAM cell 100 above the blocking temperature TBS (but below TBR), thereby unpinning the magnetization of the storage layer 106 to allow writing, such as by applying a magnetic field. The MRAM cell 100 is then cooled to below the blocking temperature TBS with the magnetic field applied, such that the magnetization of the storage layer 106 is retained in its written direction.
- TBS thermally assisted switching
- Each of the pinning layers 104 and 1 12 includes, or is formed of, a magnetic material and, in particu lar, a magnetic material of the antiferromagnetic type.
- suitable antiferromagnetic materials include transition metals and their alloys.
- suitable antiferromagnetic materials include alloys based on manganese ("Mn"), such as alloys based on iridium (“Ir") and Mn (e.g., IrMn); alloys based on Fe and Mn (e.g., FeMn); alloys based on platinum (“Pt”) and Mn (e.g., PtMn); and alloys based on Ni and Mn (e.g., NiMn).
- the pinning layer 104 can include an alloy based on Ir and Mn (or based on Fe and Mn) with a blocking temperature TBS in the range of about 120°C to about 220°C or about 150°C to about 200°C, and the pinning layer 112 can include an alloy based on Pt and Mn (or based on Ni and Mn) with a blocking temperature TBR in the range of about 300°C to about 350°C.
- the MRAM cell 100 further includes a cap layer 1 14, which is adjacent to the pinning layer 104 and forms an upper portion of the MRAM cell 100.
- the cap layer 114 provides electrical connectivity, as well as either, or both, thermal insulation and a protective function for underlying layers during manufacturing of the MRAM cell 100, and includes, or is formed of, an electrically conductive material.
- suitable electrically conductive materials include metals, such as copper, aluminum, Tantalum, Tantalum Nitride and platinum; and alloys.
- a thickness of the cap layer 114 can be in the nm range, such as from about 1 nm to about 100 nm.
- MRAM cell 100 For ease of presentation and to motivate certain advantages and functionalities a single M RAM cell 100 is illustrated, although it is contemplated that multiple MRAM cells can be included, such as in the form of an array. It should also be appreciated that the individual layers are not drawn to scale.
- the relative positioning of the storage layer 106 and the reference layer 1 10 can be reversed, with the reference layer 1 10 disposed above the storage layer 106.
- either, or both, of the storage layer 106 and the reference layer 110 can include multiple sub-layers in a fashion similar to that of the so-called synthetic antiferromagnetic layer.
- either, or both, of the pinning layers 104 and 112 can be omitted, and the cap layer 114 also can be omitted.
- next operation is to perform a first magnetic stack etch 12.
- Figure 3 illustrates the result of such etch.
- the first magnetic stack etch is stopped immediately after the tunnel layer 108 to form exposed magnetic layers 104, 106 and 108.
- the etch may be a physical etch (e.g., using an Ion Beam Etching tool) or a reactive etch (e.g., using a Reactive Ion Etching tool) or a combination of both techniques.
- the etch stop may be based on end point detection, time or both.
- the etch stop may be at any magnetic layer.
- Figure 4 illustrates a deposited isolating liner 400.
- the isolating liner 400 protects magnetic layers 104, 106 and 108.
- the isolating liner 400 may be a thin layer of dielectric materials, such as SiN or Oxide.
- the isolating liner 400 may be deposited or spun on the device.
- the thickness of the isolating liner may be tens to hundreds of Angstroms, in this example, observe that the liner 400 protects the layers 104, 106 and 108 and covers the unetched layer 110.
- the isolating liner may be configured to protect any combination of magnetic layers.
- the final operation of Figure 1 is to perform a second magnetic stack etch 16.
- the second magnetic stack etch may be a physical etch, a reactive etch or a combination thereof.
- Figure 5 illustrates the results of this operation.
- the figure illustrates the etching of the reference layer 1 10 and the pinning layer 112, which are now exposed magnetic layers.
- the isolating liner 400 remains on the sidewalks of the stack. Sputtered material 500 from the second magnetic stack etch accumulates on the deposited dielectric liner 400. However, the liner prevents shunting of magnetic layers across the tunnel barrier layer 108.
- the liner 400 also protects the already etched layers from chemical attack and damage due to continuous exposure to reactive gases and/or physical erosion.
- liner application is not restricted to a single deposition during a magnetic etch process. Liner application may be repeated. For example, an etch can be stopped when reaching a chosen specific layer above or below the tunnel layer 108 and liner can be applied.
- the liner may be applied using a spin-on technique or a deposition technique, such as chemical vapor deposition or plasma vapor deposition.
- the liner is deposited as a thick layer (e.g., greater than 1000 Angstroms) and is then etched back using a dry, wet or combined etch.
- the technique of the invention is applicable to magnetic cells of various shapes (e.g., round, elliptical and the like).
- the liner is applied after removal of remaining photoresist and polymeric residues formed during an etch process.
- the liner does not prevent etching of the magnetic stack below the liner. Further observe that the liner does not erode completely during the second magnetic stack etch.
- the liner may be applied at temperatures appropriate for processing magnetic stack wafers.
- the liner does not cause stack damage or delamination due to high stress. Rather, the liner forms a continuous layer around protected magnetic layers, including a tunnel barrier layer.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mram Or Spin Memory Techniques (AREA)
- Hall/Mr Elements (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201361776739P | 2013-03-11 | 2013-03-11 | |
PCT/US2014/022677 WO2014164520A1 (en) | 2013-03-11 | 2014-03-10 | Magnetic random access memory cells with isolating liners |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2973726A1 true EP2973726A1 (en) | 2016-01-20 |
EP2973726A4 EP2973726A4 (en) | 2016-11-30 |
Family
ID=51486810
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP14779176.8A Withdrawn EP2973726A4 (en) | 2013-03-11 | 2014-03-10 | Magnetic random access memory cells with isolating liners |
Country Status (4)
Country | Link |
---|---|
US (1) | US9059400B2 (en) |
EP (1) | EP2973726A4 (en) |
AR (1) | AR095247A1 (en) |
WO (1) | WO2014164520A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9564575B2 (en) * | 2014-12-30 | 2017-02-07 | Globalfoundries Singapore Pte. Ltd. | Dual encapsulation integration scheme for fabricating integrated circuits with magnetic random access memory structures |
US10256399B2 (en) | 2016-05-18 | 2019-04-09 | International Business Machines Corporation | Fabricating a cap layer for a magnetic random access memory (MRAM) device |
WO2019005082A1 (en) * | 2017-06-29 | 2019-01-03 | Intel Corporation | Magnetic tunneling junction devices with sidewall getter |
CN110098321B (en) * | 2018-01-30 | 2023-07-04 | 上海磁宇信息科技有限公司 | Method for preparing magnetic random access memory conductive hard mask |
US11665974B2 (en) * | 2021-01-27 | 2023-05-30 | International Business Machines Corporation | MRAM containing magnetic top contact |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6413788B1 (en) * | 2001-02-28 | 2002-07-02 | Micron Technology, Inc. | Keepers for MRAM electrodes |
US6815248B2 (en) * | 2002-04-18 | 2004-11-09 | Infineon Technologies Ag | Material combinations for tunnel junction cap layer, tunnel junction hard mask and tunnel junction stack seed layer in MRAM processing |
US6783999B1 (en) * | 2003-06-20 | 2004-08-31 | Infineon Technologies Ag | Subtractive stud formation for MRAM manufacturing |
US6984529B2 (en) * | 2003-09-10 | 2006-01-10 | Infineon Technologies Ag | Fabrication process for a magnetic tunnel junction device |
US7112454B2 (en) * | 2003-10-14 | 2006-09-26 | Micron Technology, Inc. | System and method for reducing shorting in memory cells |
US7033881B2 (en) | 2004-06-15 | 2006-04-25 | International Business Machines Corporation | Method for fabricating magnetic field concentrators as liners around conductive wires in microelectronic devices |
US7321130B2 (en) * | 2005-06-17 | 2008-01-22 | Macronix International Co., Ltd. | Thin film fuse phase change RAM and manufacturing method |
US7842558B2 (en) * | 2006-03-02 | 2010-11-30 | Micron Technology, Inc. | Masking process for simultaneously patterning separate regions |
US7663198B2 (en) | 2006-08-29 | 2010-02-16 | Qimonda Ag | Magnetoresistive random access memory device with alternating liner magnetization orientation |
US8208288B2 (en) * | 2008-03-27 | 2012-06-26 | International Business Machines Corporation | Hybrid superconducting-magnetic memory cell and array |
US8553449B2 (en) * | 2009-01-09 | 2013-10-08 | Micron Technology, Inc. | STT-MRAM cell structures |
US8981502B2 (en) | 2010-03-29 | 2015-03-17 | Qualcomm Incorporated | Fabricating a magnetic tunnel junction storage element |
US8962493B2 (en) * | 2010-12-13 | 2015-02-24 | Crocus Technology Inc. | Magnetic random access memory cells having improved size and shape characteristics |
-
2014
- 2014-03-10 EP EP14779176.8A patent/EP2973726A4/en not_active Withdrawn
- 2014-03-10 WO PCT/US2014/022677 patent/WO2014164520A1/en active Application Filing
- 2014-03-10 US US14/203,362 patent/US9059400B2/en active Active
- 2014-03-11 AR ARP140100857A patent/AR095247A1/en unknown
Also Published As
Publication number | Publication date |
---|---|
AR095247A1 (en) | 2015-09-30 |
US20140252516A1 (en) | 2014-09-11 |
US9059400B2 (en) | 2015-06-16 |
EP2973726A4 (en) | 2016-11-30 |
WO2014164520A1 (en) | 2014-10-09 |
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